Hydroformylation of olefins

ABSTRACT

A novel, heterogeneous catalyst is useful in an improved process for the production of aldehydes and alcohols from olefinic hydrocarbons in the presence of carbon monoxide and hydrogen. The catalyst consists of a polyphenylene substrate to which are bonded diphenylphosphine ligands complexed with a metal carbonyl, such as cobalt carbonyl. The catalyst has excellent thermal stability, is essentially insoluble in the reactants or reaction products, and is active in the hydroformylation reaction at a temperature of about 195° C and a pressure of about 500 psig.

This is a division of application Ser. No. 546,323, filed Feb. 3, 1975,now U.S. Pat. No. 3,998,864.

BACKGROUND OF THE INVENTION

The hydroformylation of olefins to yield aldehydes and alcohols is awell known reaction. Typically, olefins are reacted with carbon monoxideand hydrogen at a temperature of from about 100° C. to about 300° C. anda pressure of from about 1,000 psig to about 4,500 psig in the presenceof a soluble, homogeneous catalyst such as cobalt octacarbonyl. Highreaction pressures are necessary with such prior art catalysts toprevent decomposition of the catalyst. To overcome this disadvantage,metal carbonyl catalysts have been complexed with certain ligands toprovide catalysts that are more stable and are effective at pressures aslow as one atmosphere. Thus, for example, U.S. Pat. No. 3,239,569discloses that cobalt carbonyl can be complexed with stabilizingphosphorus-containing ligands such as trialkylphosphines to yieldcatalysts that are highly effective at low pressure. Also, U.S. Pat. No.3,239,566 discloses catalysts that are stable and active at low pressureconsisting of ruthenium or rhodium in complex combination with carbonmonoxide and trialkylphosphines. All of these catalysts, however, sufferfrom the disadvantage that they are soluble, so that time consuming andcostly catalyst separation and recovery steps must be employed.

Several heterogeneous hydroformylation catalyst have been disclosed inan attempt to avoid the problems of catalyst separation and recovery.U.S. Pat. No. 3,487,112, for example, teaches the preparation of aruthenium carbonyl catalyst complexed with an alkylphosphine, or analkylarsine, supported on alumina or carbon. Netherlands Pat. No.70/16532 discloses silica or silica-alumina as a support forhydroformylation catalysts. And Netherlands Pat. No. 70/06740 disclosespolystyrene and polyvinyl chloride as catalysts supports. Still otherheterogeneous catalysts are disclosed in German Pat. No. 2,000,829 andNetherlands Pat. No. 70/18322. Some of the above-cited catalysts involvea reversible adsorption of the metal carbonyl catalyst on an amorphoussolid; others involve the incorporation of the catalyst ligand into apolymer backbone. In the first instance, the catalyst is easily leachedaway from the support by hydroformylation reactants and reactionproducts; in the second instance, conventional polymers such aspolystyrene and polyvinyl chloride are partially soluble in the reactionmixture and in addition have poor thermal stability at the elevatedtemperatures required for hydroformylation.

SUMMARY OF THE INVENTION

This invention relates to a novel, heterogeneous catalyst that is usefulin an improved process for the production of aldehydes and alcohols fromolefinic hydrocarbons in the presence of carbon monoxide and hydrogen.The catalyst is prepared from a polyarylene substrate having a numberaverage molecular weight in the range of about 1,000 to about 10,000,preferably a number average molecular weight in the range of about 1,000to about 3,000. Diaryl or dialkyl phosphine groups are bonded to thepolymer substrate chain and these groups are used as ligands to complexmetal carbonyls such as cobalt, rhodium, ruthenium, osmium, iridium, andiron carbonyls.

The amount of phosphorus incorporated into the polymer is dependent onthe balance between maximizing catalytic activity and minimizing changesin the desirable insolubility and high thermal stability of the polymer.A suitable balance is achieved by incorporating phosphine groups in thepolymer in amounts such that the ratio of aryl groups in the polymer tophosphorus atoms is in the range of about 1 to about 20, preferably inthe range of about 5 to about 10.

Similarly, the amount of metal carbonyl to incorporate into the finalcatalyst depends on the balance between maximum catalytic activity perunit weight of catalyst and the possibility of metal loss from thecatalyst. It is generally desirable to have an excess of phosphinegroups relative to metal atoms so that if some metal carbonyl is lost bydissociation, there are ample phosphine sites available to re-complexthe metal carbonyl from solution. Thus, a suitable ratio of phosphorusatoms to metal atoms is in the range of from about 1 to about 20,preferably in the range of about 2 to about 10.

The catalyst prepared as described above has the advantages over priorart catalyst in that it is completely heterogeneous: it does not exhibiteven partial solubility nor does it swell on exposure to reactants orproducts in the hydroformylation reaction. Furthermore, the catalyst ismore thermally stable than prior art catalysts prepared, for example,with a polystyrene or polyvinyl chloride substrate. And the polyarylenesubstrate employed in the preparation of the catalyst is, of itself,catalytically inert and does not catalyze undesirable side reactions.

The catalyst of this invention, being completely heterogeneous, providesan improved hydroformylation process in that costly catalyst separationand recovery steps are eliminated. The catalyst can be employed in theproduction of aldehydes and alcohols by contacting an olefinichydrocarbon with carbon monoxide and hydrogen under conditions wellknown for the hydroformylation reaction. Typically, reaction conditionscomprising temperatures in the range of about 100° to about 300° C. andpressures in the range of about 10 to about 2,000 psig are utilized.

The amount of catalyst to be used in the reaction is not critical andmay vary over a wide range; for example, olefin to catalyst weightratios between 500:1 and 1:1 are suitable. Particularly suitable areolefin to catalyst weight ratios ranging from about 20:1 to about 5:1.

Olefins containing 4 to 19 carbon atoms, particularly those containing 6to 10 carbon atoms are feedstocks that can be utilized advantageously.Under the conditions of the hydroformylation reaction, the olefins areconverted to aldehydes and alcohols having one more carbon atom than theolefin charged.

The mole ratios of hydrogen to carbon monoxide employed may vary widely,for example, over the range of about 1:1 to about 10:1. The specificratio to be used will be governed in part by the nature of the reactionproducts desired. For example, if an aldehyde product is desired, asuitable mole ratio of hydrogen to carbon monoxide is 1; if an alcoholis the desired product, a suitable mole ratio is 2.

The liquid reaction products are readily separated from the catalyst bydecantation or filtration and may be purified by distillation or otherconventional means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polyarylenes utilized in the preparation of the catalysts of thisinvention are disclosed in U.S. Pat. Nos. 3,792,099; 3,798,281; and3,855,332 which are incorporated herein by reference. The polyarylenesare prepared, for example, by treating an aromatic hydrocarbon withhydrogen in the presence of an Al₂ O₃ -SiO₂ -MoO₃ catalyst system at atemperature of at least 800° F. and a pressure of at least 600 psig. Aparticularly useful polyarylene is polyphenylene prepared as disclosedin U.S. Pat. No. 3,798,281 by reacting biphenyl and hydrogen in thepresence of an Al₂ O₃ -SiO₂ catalyst impregnated with 2% MoO₃. Thereaction is carried out in a stirred autoclave for 6 hours at a peaktemperature of 1,085° F. and a maximum pressure of 1,700 psig. After thepolymerization is concluded, the crude product is dissolved in1,2,4-trichlorobenzene and filtered to remove catalyst. The polymer isprecipitated out by addition of n-pentane, filtered, and washed withn-pentane. The polymer is then dried at 100° C. for 24 hours. Thepolymer is a branched polyphenylene comprising benzene ring structuresbonded into a polymer chain wherein the amount of benzene ringstructures bonded to three or more other benzene ring structures is from15 to 25 percent by weight, the amount of benzene ring structures bondedto two other benzene ring structures is from 45 to 65 percent by weight,and the amount of benzene ring structures bonded through the metaposition to two other benzene ring structures is from 15 to 30 percentby weight, with the remaining benzene ring structures being bonded toonly one other benzene ring structure. The catalyst was prepared by thereaction depicted schematically as follows: ##STR1## where φ is phenyland x is a set of values such that the molecular weight of the polymerbackbone ranges from about 1,000 to about 10,000.

EXAMPLE I

Ten grams of polyphenylene prepared in the above-described manner andhaving a number average molecular weight of 2,000 was placed in a 500 mlfluted flask fitted with a stirrer, drop funnel, reflux condenser, andthermometer. One hundred-fifty ml 1,2,4-trichlorobenzene was added andthe mixture was stirred to dissolve the polymer. A small amount, 0.1 g.of iodine was added to the flask and then 4.2 g bromine was addeddropwise through the dropping funnel over a 10 minute period. Theresulting solution was heated to 60° C. for 1 hour and then stirredovernight at room temperature. The mixture was dissolved in CH₂ Cl₂ andextracted with 100 ml of 10% aqueous NaOH. The CH₂ Cl₂ was evaporatedoff and the residue was poured into 500 ml n-pentane. After drying, 8.5g of brown solid was obtained which contained 16.3 weight percentbromine.

The brominated polymer was dissolved in 1,000 ml of dry benzene in a twoliter flask fitted with a stirrer, reflux condenser, vapor by-passaddition funnel, and an inlet for an inert gas. An atmosphere of argonwas maintained throughout the reaction. Twenty grams of 21.5 weightpercent solution of n-butyl lithium in n-hexane was added over a 30minute period. The mixture was heated to 35°-40° C. for 1.5 hours withstirring, and then stirred overnight at room temperature. Fifteen gramsof diphenylchlorophosphine was then added to the reaction mixture andthis was stirred at room temperature for 1 hour, and at 35°-40° C. for30 minutes. The mixture was dissolved in 2,500 ml of CH₂ Cl₂ and washedonce with 100 ml water. The solution was dried over anhydrous MgSO₄, theCH₂ Cl₂ evaporated, and the residue poured into two liters of n-heptaneto precipitate the phosphinated polymer. The solid was removed byfiltration, washed with fresh heptane, and dried under vacuum at roomtemperature. The brown solid weighed 6.7g and contained 1.92% bromineand 4.36% phosphorus. It was stored under a dry nitrogen atmosphere.

In a one liter autoclave were placed 320 g heptane, 6.7 g of thephosphinated polymer prepared above, and 0.5 g of dicobalt octacarbonyl.The autoclave was sealed and pressured to 200 psig with a H₂ /CO mixturehaving a mole ratio of 2:1. The contents were stirred at 2,000 rpm andheated to 195° C., whereupon the pressure rose to 400 psig. Thesereaction conditions were maintained for two hours.

To the catalyst mixture prepared above was added 67.2 g (.60 mole) ofoctene-1 and 40 g of n-decane (employed as an internal standard for gaschromatography analysis). The reaction mixture in the autoclave washeated to 195° C. and the pressure was increased to 500 psig with a H₂/CO mixture having a mole ratio of 2:1. These conditions were maintainedfor 2.5 hours. Another 0.5 g of dicobalt octacarbonyl was added and thereaction continued for six hours. The reactor was then cooled and thereaction mixture was then filtered to separate the catalyst from theliquid product.

The recovered catalyst contained 1.09 weight percent cobalt and 4.21weight percent phosphorus. The ratio of phenyl groups to phosphorusatoms was 7.0 and the ratio of phosphorus atoms to cobalt atoms was 7.4.

Analysis of the liquid reaction mixture is given in the following table:

    ______________________________________                                        n-Octenes        47.9 g   (.428 mole)                                         n-Octane         3.3 g    (.0293 mole)                                        C.sub.9 Aldehydes                                                                              11.2 g   (.0789 mole)                                        C.sub.9 Alcohols 4.5 g    (.0315 mole)                                        Total                     (.568 mole)                                         Straight chain material                                                       in aldehyde and alcohol                                                       product          38%                                                          Cobalt           <5 ppm                                                       ______________________________________                                    

Based on these data the hydroformylation reaction may be summarized asfollows:

    ______________________________________                                        Material Balance     95 mole %                                                Conversion of Octenes                                                                              29 mole %                                                Selectivities:                                                                 To Octane           17 mole %                                                 To C.sub.9 Aldehydes                                                                              46 mole %                                                 To C.sub.9 Alcohols 18 mole %                                                Total                81 mole %                                                ______________________________________                                    

The data tabulated above indicate that the catalyst of this invention isactive for the hydroformylation reaction, as evidenced by the formationof aldehyde and alcohol; and is heterogeneous, as evidenced by theextremely low amount of cobalt in the liquid product.

The sequence of reactions above is given by way of illustration only.Other preparative methods to obtain the desired catalyst composition canbe employed and will be evident to those skilled in the art.

I claim:
 1. A process for the production of aldehydes and alcohols whichcomprises contacting an olefinic hydrocarbon having about 4 to about 19carbon atoms with carbon monoxide and hydrogen at the temperature ofabout 100°-300° C and a pressure of about 10-2,000 psig in the presenceof a heterogeneous catalyst consisting of a polyphenylene comprisingbenzene ring structures bonded into a polymer chain wherein the amountof benzene ring structures bonded to three or more other benzene ringstructures is from 15 to 25 percent by weight, the amount of benzenering structures bonded to two other benzene ring structures is from 45to 65 percent by weight, and the amount of benzene ring structures isbonded through the meta position to two other benzene ring structures isfrom 15 to 30 percent by weight, with the remaining benzene ringstructures being bonded to only one other benzene ring structure, saidpolyphenylene having a number average molecular weight in the range ofabout 1,000 to about 10,000, said polyphenylene having --PR₂substituents, where R is a phenyl or an alkyl group in amounts such thatthe ratio of aryl groups to phosphorus atoms is in the range of about1.0 to about 20, said --PR₂ groups being complexed with a metal carbonylcompound selected from the group consisting of cobalt, rhodium,ruthenium, osmium, iridium, and iron carbonyls in amounts such that theratio of phosphorus atoms to metal atoms is in the range of from about 1to about
 20. 2. A process for the production of aliphatic aldehydes andalcohols having from about 7 to about 11 carbon atoms which comprisescontacting an olefinic hydrocarbon having from about 6 to about 10carbon atoms with carbon monoxide and hydrogen at a temperature of about100°-300° C and a pressure of about 10-2,000 psig in the presence of aheterogeneous catalyst consisting of a polyphenylene comprising benzenering structures bonded into a polymer chain wherein the amount ofbenzene ring structures bonded to three or more other benzene ringstructures is from 15 to 25 percent by weight, the amount of benzenering structures bonded to two other benzene ring structures is from 45to 65 percent by weight, and the amount of benzene ring structuresbonded through the meta position to two other benzene ring structures isfrom 15 to 30 percent by weight, with the remaining benzene ringstructures being bonded to only one other benzene ring structure, saidpolyphenylene having a number average molecular weight in the range ofabout 1,000 to about 3,000, said polyphenylene having --PR₂substituents, where R is a phenyl or alkyl group, in amounts such thatthe ratio of aryl groups to phosphorus atoms is in the range of about 1to about 50, said --PR₂ substituents being complexed with cobaltcarbonyl in amounts such that the ratio of phosphorus atoms to cobaltatoms is in the range of from about 2 to about
 10. 3. A process for theproduction of a mixture of nonyl aldehydes and nonyl alcohols whichcomprises contacting octene-1 with carbon monoxide and hydrogen at atemperature of about 195° C and a pressure of about 500 psig with aheterogeneous catalyst consisting of polyphenylene containing benzenering structures bonded into a polymer chain wherein the amount ofbenzene ring structures bonded to three or more other benzene ringstructures is from 15 to 25 percent by weight, the amount of benzenering structures bonded to two other benzene ring structures if from 45to 65 percent by weight, and the amount of benzene ring structuresbonded through the meta position to two other benzene ring structures isfrom 15 to 30 percent by weight, with the remaining benzene ringstructures being bonded to only one other benzene ring structure, saidpolyphenylene having a number average molecular weight of about 2,000,said polyphenylene --P(C₆ H₅)₂ substituents in amounts such that thephosphorus content is about 4.2 wt. %, said --P(C₆ H₅)₂ substituentsbeing complexed with cobalt carbinyl in amounts such that the cobaltcontent is about 1.1 wt. %, the ratio of phenyl groups to phosphorusatoms being about 7.0, and the ratio of phosphorus atoms to cobalt atomsbeing about 7.4.